Field of Invention
The invention relates to a boom mounting assembly for attachment to an agricultural application machine.
Description of Related Art
Agricultural application machines such as crop sprayers comprise a large volume tank carried on a chassis. Such machines can be trailed behind a tractor or provided as a self-propelled unit having an integral cab and engine. The machine further comprises an extending boom which provides a transverse line of uniformly spaced spray nozzles connected by pipes to the tank. During operation the application machine is moved across fields of crops such as cereals and maize to apply liquid fertilizer or chemical treatment such as herbicides, fungicides and pesticides to the crop in a controlled manner.
The boom typically ranges from 10 to 40 meters in length when fully extended and is supported at an intermediate section of around 4 meters in length by a boom mounting assembly. This leaves a significant portion of the boom unsupported when fully extended and relying on only the rigidity of the boom structure to remain in position. The effects of forces applied to the extremities of the boom are exacerbated due to the moment of the unsupported portion.
Movement of the boom is known to include yaw, pitch and roll. ‘Yaw’ is pivoting movement of the boom around a central vertical axis. In other words, the left-hand side of the boom moves forwards whilst the right-hand side moves rearwards. Excessive yaw movement can result in uneven application of the spray to areas of the field. ‘Pitch’ is movement of the entire boom about a transverse axis and typically results from acceleration or deceleration of the vehicle. Excessive yaw movement can also result in uneven spray application. ‘Roll’ is movement of the boom around a longitudinal axis and typically results from the vehicle being driven over uneven terrain. Left uncontrolled, excessive roll can result in the extremities of the boom striking the ground thus risking damage to both the boom and the crop.
Oscillations in any direction can increase in amplitude to the extent where the machine must be stopped and restarted leading to inconvenience for the operator and an inefficient working approach.
To control the oscillations and movement of the boom extremities damping means are often provided to damp movement of the boom mounting assembly relative to the machine. Attempts have been made to control the various oscillations in a boom resulting in rather complex suspension and damping systems. Although capable of controlling movements of the boom, known systems comprise many components adding to the overall weight and complexity of the assembly.